A receiver of double conversion system for performing frequency conversion two times for a received broadcast wave by using two mixing circuits is conventionally known (for example, see pages 2 to 3, FIGS. 1 to 4 of Japanese Patent Laid-Open No. 2000-174653). The first stage mixing circuit converts the broadcast wave to a higher frequency signal so as to enable image interference to be easily removed, as a result of which excellent interference characteristics can be realized with a non-tuning type receiver without an antenna tuning circuit and an RF tuning circuit.
In the above-described patent gazette document, a prior art is also disclosed in which the reception sensitivity and the interference characteristic are further improved in the receiver of double conversion system by making a signal obtained by applying high frequency amplification to a broadcast wave received with an antenna tuned before the signal is inputted to the first stage mixing circuit. The tuning of the signal before it is inputted to the first stage mixing circuit makes it possible to prevent a radio wave of a broadcasting station whose reception is not desired and a noise from entering the first stage mixing circuit.
In the receiver disclosed in Japanese Patent Laid-Open No. 2000-174653 described above, however, since the signal received via the antenna is made to pass the tuning circuit after being subjected to the high frequency amplification, there is a problem in that unwanted components such as a radio wave of a broadcasting station whose reception is not desired and a noise, when included in the signal received by the antenna, are also amplified. In the above-described receiver in which the tuning circuit is configured by combining a tuning coil with a variable-capacitance diode, the antenna is also separately provided. For example, a rod antenna is generally used as the antenna, but in this case, there is a problem in that both the rod antenna and the tuning coil are needed, causing the number of components to be increased.